Temperature controlled coolbox


by nusnel @ instructables.com:

For my monthly maker column in Dutch newspaper “De Volkskrant”, I made a coolbox in which you can control the temperature in three separate compartments to keep craft beer at just the right temperature.

The contraption I build uses three Peltier-elements to cool, an old desktop computers power source, an LCD to show both the measured and the set temperature and finally an Arduino to tie it all together.

Temperature controlled coolbox – [Link]

Arduino Time-Lapse Panorama Controller


by oliverb @ instructables.com:

The Arduino controls a Geared Stepper Motor 28BYJ-48 via a ULN2003 Stepper Motor Driver Board. The 4×20 I2C LCD display and 5 micro switches form the interface to the Arduino. The controller has a Manfrotto 200PL-14 quick release tripod mount for attachment to my tripod and other mounting hardware fitted with a Manfrotto 323 Quick Release Clamp Adapter. Power is provided by a 50000mah USB Power Bank Battery Pack.

Arduino Time-Lapse Panorama Controller – [Link]

[Article] Basic Diode Types


In this article we will discuss about the various types of diodes, their working principle and their common uses. We will cover many common diode types, such as P-N junction diode, Zener diode, Schottky diode, LED and laser diodes, photo diode, varactor diode, avalanche diode, PIN diode etc. Feel free to leave a comment with other types of diodes you know.

P-N Junction Diode


This is the most common type of diode and acts as one way gate to current flow. The current flows from anode (A) to cathode (C) and comes in two types depending on the material used, silicon and germanium. They both need a forward-bias voltage to contact which is in the range of 0.6-1.7V for silicon and 0.2-0.4V for germanium. Common uses are: voltage rectification, transient suspension, voltage multiplication, voltage regulation etc.

Zener Diode


Zener diode acts like a p-n junction diode if forward-biased and conducts from anode (A) to cathode (C) but will also conduct in the opposite direction if the applied voltage exceeds the zener’s breakout voltage Vz. Common breakout voltages are 1.2V, 3V, 5.1V, 6.3V, 9V, 12V etc. Common uses are: voltage regulation, waveform clipping, voltage shifting, voltage reference etc. Often they are used in series and with opposite directions with p-n junction diodes to balance the temperature coefficient response.

Schottky Diode


This kind of diodes have similar operation with p-n junction diodes but are constructed with metal semiconductor junction instead of a p-n junction. They have a lower forward voltage drop (0.15-0.45V) than p-n junction diodes and way lower junction capacity that results for quicker switching times. Common uses are: low loss rectification, high frequency applications, RF applications, switchmode power supplies, mixers and detectors.

LED and Laser Diodes


Light emitting diodes (LED) produce light when forward biased and they come in many different types depending on wavelength emitted (infrared, visible light and ultraviolet), power output, size and material used. A typical forward voltage is 1.7 to 4V and their wavelength spectrum is about 40nm wide. They are often used as indicators and for lighting purposes. In contrast laser diodes have a much narrower spectrum of about 1nm and fast response times and are used in fiber optic communications, CD/DVDs, barcode readers, medical uses etc.

Photo Diode


Photo diodes are able to generate current when exposed to light and current flow from cathode (C) to anode (A). When light intensity increases the current passing thought the diode also increases and they have fast response time in terms of ns. They are not as sensitive as phototransistors but they have good linearity making them ideal in use on simple light meters. Common uses are in photometry, solar cells and optical communications.

Varactor Diode


Varactor diodes are used as voltage controlled capacitors. The capacitance decreases as the reverse-bias voltage on the diode increases. We can find them on PPL (Phase locked loop), FLL (Frequency locked loop) circuits, general RF applications and tuning receivers. The junction has a capacitance in the range of pF for small variations on reverse-bias voltage.

Avalanche diode


Avalanche diodes are similar to Zener diodes, they contact when reverse biased and the reverse bias voltage exceeds the breakdown voltage. They may be similar to Zener diodes but the breakdown occurs using a different mechanism, the avalanche effect. Another difference is that they have opposite temperature coefficients. They are used in voltage references, protection, RF noise generation etc.

PIN Diodes


PIN diodes have a central un-doped region between P and N regions and they are used as RF and microwave switches. For high frequency signals PIN diode acts like a variable resistor whose value is depended on the applied dc forward-biased voltage. So, for high DC forward bias its resistance is less than an Ohm but in low forward bias the resistance is in the kOhm range.

There are also some other types of diodes available such as IMPATT, Gunn, Tunnel which are used for special purposes at high frequencies, for example on amplifiers and oscillators. The physics of such diodes is complex and beyond the scope of this article. I hope you get an idea of the basic types of diodes available and feel free to leave a comment.

Driving LEDs


Emanuele @ dev.emcelettronica.com published an article on how to drive LEDs:

The LEDs (Light Emitting Diode) are diodes whose basic characteristic is the ability to emit light when they are passed through a current that flows from P to N region. At each recombination between the charge carriers (electrons and holes), on PN junction region, a photo emission is generated, and the total quantity of emitted photons, and therefore the light intensity, is proportional to the current intensity that passes through them. The emitted light has a spectrum – wavelengths distribution – that is defined according to the materials used in the realization of the diode PN junction, although it partially depends on the current intensity and on the junction temperature.

Driving LEDs – [Link]

Make a Weather Station With a Raspberry Pi 2


Jeremy Morgan @ jeremymorgan.com writes:

Today I’m going to show you how to make sort of a mini weather station with a Raspberry Pi. This is an ongoing project of mine that I’ve been tinkering with so I’ll share my learnings with you. It started with a project I wrote about last month, and is an improvement on it.

A core part of the “Internet of Things” movement is the idea of devices that gather data and send it to the Internet. That data is then acted on or observed for later. It’s a simple concept and has been going on for a while but lately it’s been getting cheaper and easier to do. This project is a great example of that.

Make a Weather Station With a Raspberry Pi 2 – [Link]

PCB stencil jig


Gonazar’s PCB stencil jig:

My solution to making a PCB stencil jig.
I need this to do a run of ~30 small boards I got from DirtyPCB who also provided me with the stencil. However, I know that I’m going to be making more later with a new revision so I wanted a jig that I could later reuse with a new design.
One of the challenges of making a pcb jig is alignment and finding something to lie next to the pcb so the stencil doesn’t bow/bend from unsupported areas.
So my design uses two 1/8″ thick acrylic frames on a hinge. The top frame has a large opening to work with the stencil and the bottom frame has a fixed rectangular hole. This hole is for placing a 3D printed jig that perfectly matches the PCB shape and thickness. It’s also exactly the dimension of a 8.5″x11″ cut into 8 pieces. This way I can lock in my PCB and align my stencil, then adjust the height by shimming it with pieces of paper underneath.

PCB stencil jig – [Link]


Can a current flow even up the hill?


Of course it can, even apeak. So if you connect leads from the bottom side via a PCB connector, you don´t have to worry about the current…

Should you however be afraid of accidental fall off of the connector (it will certainly hold on if there are no vibrations, shocks or unpredictable tension to leads), then for your peace of mind we recommend you to use connectors that can be secured by a screw.

Naturally, devices exposed to vibrations are much more frequent (for example with a motor) or even devices which are often subjeted to transport – for all such cases a connector with a flange (and integrated screw) finds its place.

Such solution is also offered by a well-known producer of terminal blocks – EUROCLAMP. For example for currents up to 8 Amps and voltages to 160V, these novelties from our stock are suitable:

  • SH04-3,5-K (4-pole plug-in connector for cable, with a 3.5 mm pitch, with a flange and screw)
  • PV04-3,5-V-K (a mating piece to SH04-3,5 for a PCB with a flange and screw) For a real certain feeling, this component can be screwed to a PCB by a self tapping screw ( ISO1481-ST 2,2×4,5(6,5)C screw, not included)

A screw also prevents accidental disconnection (it´s only possible with a screwdriver). In extreme case, the screws can be replaced by security head screws… (but this perhaps no – if you deal with a critical device – then use some more efficient precautions).

Detailed information can be found in the SHxx-3,5-K and PVxx-3,5-V-K datasheets.

Can a current flow even up the hill? – [Link]

High Speed Ecosystem Support and Calamity Monitoring System

The innovation of equipment for calamity detection and monitoring are quite rampant. It is because of consecutive aggression of storms and earthquakes in different parts of the world. As to observe the different scenarios, these are not merely natural causes, there are some or most of it is manmade. A good example of it is a storm, which is the combination of hot and cold air. These hot and cold airs are natural but the rapid change of air temperature is not natural. Aside from air, water is another major contributor to global warming. Abnormalities that happened to the body of water affect the entire ecosystem, which also affect both living and nonliving things. With such cases, the environment needs care from people. This simple design of ecosystem support and calamity detection will be a great help in protecting the nature and preventing major disasters from occurring. It features two sensing parameters such as pressure and pH level. It has Fast-mode Plus (Fm+) capability on its buses, which can be configured to communicate up to 64 slaves in one serial sequence with no intervention from the CPU. It can communicate remotely and locally where GSM is unavailable.

The design is comprised of SST89E52RC-33-C-PIE legacy microcontroller as the main processor of the device. It is interfaced with the PCA9661 parallel bus to 1 channel Fm+ I2C-bus controller with 74HC237D as the decoder. This interface provides the ports for the sensors, which it communicates at high speed data transfer. The two sensor attached to the I2C-bus controller are SEN-10972 pH sensor and MPL115A1T1 miniature I2C digital barometer. The SEN-10972 pH sensor is used to monitor the pH level of water in which a change of pH level signifies abnormalities or some toxic chemicals that are present in water. The MPL115A1T1 barometer is used to monitor the possibilities of a developing tropical storm or typhoon. The GSM module is for remote data communication with central station or any portable device that is GSM communication capable. In case of a local monitoring and GSM signal dead zone, a built in RF transmitter will trigger to transmit data to any portable device or stations within the range of RF transmission.

The innovation of this device will surely help both the people and environment. It can result to a lesser number of casualties and agricultural damages. It can help the development of municipalities, cities, and/or even nations since it saves a lot of investments and other types of income. This design can be integrated to several developments that can provide more efficient and useful technology instrument for the people and the environment.

High Speed Ecosystem Support and Calamity Monitoring System – [Link]

18 PIN PIC Development Board


The PIC 18 PIN (DIP) Development / Evaluations Board demonstrates the capabilities of Microchip’s 8-bit microcontrollers, specifically, 18 Pin PIC16F1847. It can be used as a standalone demonstration board with a programmed part. With this board you can develop and prototype with all Microchip’s 18 PIN PIC microcontrollers. The board has a Reset switch and status LEDs. On board 3.3 V and 5V DC regulators allows using 3V and 5V PICs, This board support both 3.3V low power and normal 5V operation. All I/O Pins out with 2 x female headers

Development Board Features:

  • 16 I/O Ports
  • Onboard 5V and 3.3V Supply
  • 3.3V or 5V Supply selection by jumper
  • Dual line I/O
  • On board Power Indication
  • On-board ICSP Port (PICKIT2 Standard Programming Port)
  • Well labeled legends
  • All outputs has provision for LEDs for output indication
  • Replaceable PIC Microcontroller,
  • Crystal and capacitor mounting under the PCB

18 PIN PIC Development Board – [Link]

ESP8266 remote controlled sockets


Rui Santos published a new project, an ESP8266 remote controlled sockets:

In this project your’re going to build a web server with an ESP8266 that can control remotely any sockets (safely!).

ESP8266 remote controlled sockets – [Link]